The Administrative Core will be responsible for providing scientific administration and coordination, fiscal oversight and administrative support for this Costimulation PPG. The Administrative Core will coordinate PPG scientific group meetings among investigators at Brigham and Women's Hospital, Dana-Farber Cancer Institute, Joslin Diabetes Center, Harvard Medical School, University of Minnesota, and Emory University using video conferencing and telephone conference calls. The Administrative Core takes on added importance in this PPG due to the geographic distance between some of the PPG investigators, and will provide effective communication services. In addition, the Administrative Core will arrange an annual PPG meeting for investigators in Boston. Administratively, this Core will coordinate annual progress reports and renewal of sub-contract agreements, and will liaison between the grants offices of the various institutions and the Harvard Medical School Sponsored Programs Administration office. Arlene Sharpe, together with Mohamed Sayegh, and Harvard Medical School, are responsible for this application and for the collaborative research activities described.